Such a shading system is disclosed in DE 10 2011 076 892 A1. The known shading system is intended for a split side window of a passenger vehicle. The shading system includes a flexible main shading structure and a flexible auxiliary shading structure. Both the main shading structure and the auxiliary shading structure are each mounted on a distinct winding shaft for winding up and off. The two winding shafts are positioned fixed in location in the region of the side window and mechanically coupled to each other by a gear mechanism so that the two winding shafts are in operative connection with each other. The one winding shaft for the main shading structure is oriented approximately horizontally in the region of a window sill. The other winding shaft for the auxiliary shading structure is oriented approximately vertically in the region of a window bar. The main shading structure and the auxiliary shading structure are manually transferable from a stowed position to the shading position, wherein the auxiliary shading structure is associated with a supporting spring drive which, upon a displacement of the main shading structure in the direction towards the shading position, necessarily causes an analogous displacement of the auxiliary shading structure from the stowed position to the shading position.